Inherit summon:
Inherit summons are the monsters that special summon themselves due to conditions or game mechanics. These special summons never start a chain and can only be done during your main phase. These cards are special summoned from the hand unless otherwise specified. This is for cards like cybernetics dragon, genex ally birdman, and grapha, dragon lord of dark world. Contact fusions, synchro summons, and xyz summons fall into this category.
A card effect that negates a special summon does work against these cards. Cards such as divine wrath however do not because they are considered conditions, not effects.
Card effect special summons:
These summons are at the resolution of a card effect. Fusion summons and ritual summons fall in this category.
These special summons can NOT be negated, however the effect that special summons a monster can stop it.
Summon response window:
No matter how they are summoned they are all considered being summoned. This leads to cards that say "when a monster(s) is summoned...." sometimes multiple card effects will start a chain that includes a monster summon we must pay attention to the chain links
Anything chain link 2 or higher can not be hit by bottomless or torrential due to those effects activating during the middle of a chain in this situation.